Sternal angle

The sternal angle (also known as the angle of Louis or manubriosternal junction) is the synarthrotic joint formed by the articulation of the manubrium and the body of the sternum.

The sternal angle is a palpable clinical landmark in surface anatomy.

Anatomy

The sternal angle, which varies around 162 degrees in males, marks the approximate level of the 2nd pair of costal cartilages, which attach to the second ribs, and the level of the intervertebral disc between T4 and T5. In clinical applications, the sternal angle can be palpated at the T4 vertebral level.

The sternal angle is used in the definition of the thoracic plane. This marks the level of a number of other anatomical structures:

Structures at the level of the thoracic plane

The start and end of the aortic arch The division between the superior and inferior mediastinum The upper margin of the superior vena cava The crossing of the thoracic duct The bifurcation of the trachea The bifurcation of the pulmonary trunk The level of the sternal angle The level of Rib 2 where it attaches to the sternum via the 2nd costal cartilage The body of vertebrae T4(the disc between the vertebra T4and T5) The drainage of the azygos vein into the superior vena cava

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The angle also marks a number of other features:

• Carina of the trachea is deep to the sternal angle
• Passage of the thoracic duct from right to left behind esophagus
• Ligamentum arteriosum
• Loop of left recurrent laryngeal nerve around aortic arch

The angle is in the form of a secondary cartilaginous joint (symphysis).

History

The sternal angle is also called the angle of Louis after Antoine Louis

See also

• Thoracic plane
• List of medical mnemonics

External links

• Anatomy photo:18:st-0212 at the SUNY Downstate Medical Center - "Thoracic Wall: Bones"